论文标题
Protostellar在最早的阶段（诗人）流出。 iv。 22 GHz H2O masers的统计特性
Protostellar Outflows at the EarliesT Stages (POETS). IV. Statistical properties of the 22 GHz H2O masers
论文作者
论文摘要
我们希望对单个22 GHz水层云的位置和运动进行统计研究，其特征在于少数AU之内的大小，就年轻恒星物体（YSO）的无线电热发射而言。为此，我们一直在对高质量YSO的样本（38）的最早阶段（诗人）调查进行原始的流出。水层位置和三维（3D）速度是通过非常长的基线阵列观测值确定的，分别具有少数Milliarcsec（MAS）和几公里/s的精度。通过敏感的连续jansky确定了标记YSO的原始芯的电离芯的位置非常大的阵列观测值，典型的误差为20 mas。从无线电连续体中分离水的统计数据表明，从YSO中发现了84％的masers，其中有45％的Masers在200个AU之内。因此，我们可以得出结论，22 GHz水层是YSO位置的可靠代理。 Maser发光度的分布朝低值高峰，表明大约一半的MASER人群仍未发现当前非常长的基线干涉率检测阈值为50-100 MJY/BEAM。敏感的无线电干涉仪下一代将利用这些弱的masers来改善YSO周围速度和磁场的采样。水层适当运动的平均方向为YSO发射的射流的方向提供了一个统计学上的估计值：55％的Maser正确运动均在与射流轴30度的角度内的天空定向。最后，我们表明，我们对3D maser速度的测量在统计上支持模型，其中水层发射是由平面冲击产生的，其传播方向靠近天空平面。
We wish to perform a statistical study of the location and motion of individual 22 GHz water maser cloudlets, characterized by sizes that are within a few au, with respect to the radio thermal emission from young stellar objects (YSO). For this purpose, we have been carrying out the Protostellar Outflows at the EarliesT Stages (POETS) survey of a sample (38) of high-mass YSOs. The water maser positions and three-dimensional (3D) velocities were determined through Very Long Baseline Array observations with accuracies of a few milliarcsec (mas) and a few km/s, respectively. The position of the ionized core of the protostellar wind, marking the YSO, was determined through sensitive continuum Jansky Very Large Array observations with a typical error of 20 mas. The statistic of the separation of the water masers from the radio continuum shows that 84% of the masers are found within 1000 au from the YSO and 45% of them are within 200 au. Therefore, we can conclude that the 22 GHz water masers are a reliable proxy for the YSO position. The distribution of maser luminosity is strongly peaked towards low values, indicating that about half of the maser population is still undetected with the current Very Long Baseline Interferometry detection thresholds of 50-100 mJy/beam. Next-generation, sensitive radio interferometers will exploit these weak masers for an improved sampling of the velocity and magnetic fields around the YSOs. The average direction of the water maser proper motions provides a statistically-significant estimate for the orientation of the jet emitted by the YSO: 55% of the maser proper motions are directed on the sky within an angle of 30 deg from the jet axis. Finally, we show that our measurements of 3D maser velocities statistically support models in which water maser emission arises from planar shocks with propagation direction close to the plane of the sky.
